In general, a silver halide color photographic material comprises a support coated thereon three kinds of silver halide emulsion layers which are selectively sensitized so as to be sensitive to blue light, green light and red light respectively, in the form of a multilayer structure.
In order to form a color photographic image, a silver halide color photographic material containing three color photographic couplers of yellow, magenta and cyan incorporated into the light-sensitive emulsion layers respectively is exposed imagewise and then subjected to color development processing using a color developing agent such as an aromatic primary amine. The oxidation product of an aromatic primary amine reacts with a coupler to form a dye. It is preferred that the coupler used has a good color forming property. Specifically, the coupler is desired to have a large coupling speed as possible in order to provide a high color density within a restricted developing time. Further, it is requested that dyes formed are clear cyan, magenta and yellow dyes each having less subsidiary absorption and provide a color photographic image having good color reproducibility.
On the other hand, it is also requested for color photographic images formed to have good preservability under various conditions. Such conditions for preservation include, for example, condition for preservation in a dark place influenced by humidity or heat and condition for preservation under light irradiation such as sun light, room light, etc. In addition to discoloration and fading of color images, yellowing of white background is severe problem, in particular, in color photographic materials for prints.
In order to fulfill the above-described requirements for color photographic materials, couplers play an important role as color image formers. Therefore, various investigations for improving these properties have been made by modifying coupler structures. Particularly, magenta couplers are important from the standpoint of visual sensitivity and 5-pyrazolone derivatives have been heretofore employed mainly as magenta couplers. However, color images formed therefrom have undesirable absorptions in a blue light region and a red light region in addition to desired absorption in a green light region, and thus it can not be said that these magenta couplers have satisfactory properties. Further, 5-pyrazolone derivatives are insufficient in view of image preservability since they are apt to change to yellow under light irradiation or a condition of high humidity, although they are excellent in processing stability.
On the other hand, pyrazoloazole type magenta couplers as described in Japanese Patent Application (OPI) No. 171956/84, etc. (the term "OPI" as used herein means an "unexamined published application") have superior properties in that they are excellent in light absorption characteristics of color images formed therefrom and that they provide less yellowing in white background.
However, with pyrazoloazole type magenta couplers, color density is widely changed depending on the variations in color development processing solutions. Particularly, these changes in color density are considerably large and cause severe problems in practical use in a case wherein an amount of the photographic material processed per day is varied or wherein silver chloride, silver bromide or silver chlorobromide, which do not substantially contain silver iodide is employed as silver halide.